The present invention relates to an improved control system for central and portable vacuum cleaners of the type having a vacuum blower motor and remote agitator motor. In its more particular aspects, the invention is concerned with such a system wherein a single pair of conductors may be employed to both supply power to the remote agitator motor and energize the blower motor.
This invention is an improvement in the invention forming the subject of U.S. Pat. No. 4,070,586, granted Jan. 24, 1978 to John J. Breslin, one of the coinventors herein. That patent discloses a control system wherein power is supplied and control is achieved through means of a single pair of leads. In the system of that patent, energization of the blower motor was achieved by either a transformer sensing system or the monitoring of the voltage drop in a D.C. circuit.
Another patent significant to the present invention is U.S. Pat. No. 3,525,876, Aug. 25, 1970, also granted to John J. Breslin. That patent discloses a two wire power transmission and control circuit which supplies low voltage D.C. power to an agitator motor and which uses a low voltage A.C. circuit.
The present invention is a simplification of the A.C. control and power supply circuit found in U.S. Pat. No. 4,070,586. It is an improvement over the circuit of that patent in that it results in economy of parts and labor, decreased size and weight and the avoidance of inadvertent triggering of the blower motor as the result of current leakage across the parallel wires extending to the control switch for the agitator and blower motors. Such leakage is a significant factor because of the length of the leads and may be sensed by the sensing transformer, with the result that the transformer turns on the main blower, even though the control switch is in full "off" position. This type of leakage is known as "capacitive reactance".